Vespers is a liturgy of evening prayer, one of the canonical hours in Catholic (both Latin and Eastern rites), Eastern Orthodox, Oriental Orthodox, and Lutheran liturgies. The word for this fixed prayer time comes from the Latin vesper, meaning "evening".

Vespers typically follows a set order that focuses on the performance of psalms and other biblical canticles. Eastern Orthodox liturgies advertised as 'vespers' often conclude with compline, especially the all-night vigil. Performing these liturgies together without break was also a common practice in medieval Europe, especially outside of monastic and religious communities.

Old English speakers translated the Latin word vesperas as æfensang, which became evensong in modern English. The term is now usually applied to the Anglican variant of the liturgy that combines vespers with compline, following the conception of early sixteenth-century worshippers that conceived these as a single unit. The term can also apply to the pre-Reformation form of vespers or forms of evening prayer from other denominations.

Vespers is usually prayed around sunset. In Oriental Orthodox Christianity, the office is known as Ramsho in the Indian and Syriac traditions; it is prayed facing the east by all members in these churches, both clergy and laity, being one of the seven fixed prayer times.